1. Field of the Invention
The invention relates to an apparatus for guiding a web-like material applicable to an apparatus for guiding single-faced corrugated board or liner in a corrugate machine.
2. Description of the Prior Art
A typical conventional suction-box type guiding apparatus in a corrugate machine have been illustrated in FIGS. 1 and 2. A single-faced corrugated board 1 is moved from a single facer 2 to a double facer 4 via a guiding apparatus 3, while a liner 5 is unrolled from a roll on a mill roll stand 6 and moved to the double facer 4 through the guiding apparatus 3.
It is a common measure to guide and tense the single-faced corrugated board 1 formed by the single facer 2 before the board 1 comes into the double facer 4, by means of the guiding apparatus 3. However, the provision of the guiding apparatus for imparting a tension to the liner 5 is considered as an application.
Referring to FIG. 2, a suction box 9 disposed between inlet and outlet guide rolls 7, 8 is subjected to a pressure lower than the atmospheric pressure, by means of a blower 10. A perforated plate 11 is provided on the side of the suction box 9 where the single-faced corrugated board 1 runs, and is adapted to make a smooth sliding contact with the latter. The negative pressure in the suction box 9 attracts the single-faced corrugated board 1 toward the suction box 9 to impart a tension to the single-faced corrugated board 1. The guiding apparatus for the liner is installed substantially in the same manner.
Usually, the guiding apparatus are operated with various widths of single-faced corrugated board 1 and liner 5, from the maximum width to a width about a half of the maximum width, in accordance with the size of the corrugated cardboard box which is the final product. In order to make it possible to adjust the region of negative pressure in the suction box 9, a piston 12 is attached to a screw shaft 13, motor 14 and a guide shaft 15, and is disposed at the inside of the plate 11.
However, in the conventional apparatus having the described construction, it is necessary to change the region of the negative pressure in the suction box 9 in accordance with the change of the sheet width, for otherwise absolute value of the negative pressure is undesirably reduced due to sucking of air through the bores which are located outside the width of the sheet. The change of the sheet width is usually made 50 to 100 times a day, at each of which the adjustment of the range of negative pressure in the suction box 9 has to be made. Thus, the conventional guiding apparatus requires a very troublesome work for treating sheets of various widths.
In addition, this adjustment of the range of negative pressure requires a highly complicated construction including the aforementioned piston 12, screw 13, motor 14 and the guide shaft 15, resulting in a raised cost of the apparatus.
In addition, it is necessary to provide a display device to display the region of negative pressure in the suction box, as well as a device for presetting the region of negative pressure of the next order, resulting in a further complicated construction and further raised cost of the apparatus. In addition, the aforementioned piston 12, screw shaft 13, guide shaft 15 and other associated parts can hardly be checked because they are accommodated by the suction box 9.